The major objective of the proposed research is to examine the relationships between the effects of antipsychotic drugs upon those psychological processes in schizophrenics in which psychological deficit or deviant functioning has been established and their effects upon symptomatology and morbidity. Two investigations involving chronic schizophrenics are under way. The response to drug treatment and to drug withdrawal over time in the performance of tasks reflecting attention, perception and cognition, as well as in indicants of somatic arousal, are being studied in parallel with the response at the symptom level and in terms of global improvement reflected in behavior ratings. The first of these two investigations is virtually complete. A subsidiary objective is to examine a number of performance variables with respect to the prediction of antipsychotic drug response. It is thought that from the pattern of interrelationships between drug response at the level of psychological processes and at the level of symptomatic behavior, behavioral mechanisms of drug action may be inferred. Moreover, the research may shed some light on the nature of psychological mediating mechanisms of schizophrenic disorder.